Oil-Water Interfacial Synthesis as a Benign and Safer Alternativ to Conventional Liquid-Phase Syntheses

有机合成通常在有机溶剂中进行，其中一些是有毒的、危险的或对环境有害的。对于均相合成反应，溶剂的选择往往受到溶剂所需的多种功能的限制。其中两个更重要的功能是：(1)增溶反应物、反应中间体和催化剂，以及(2)通过溶剂作为碱或催化剂配基的参与来提高速率或选择性。在工业生产聚(2，6-二甲基-1，4-苯氧基)(PPO)的基础上，2，6-二甲基苯酚的好氧偶联反应中，常使用吡啶和硝基苯作为反应介质，因为它们对二甲基苯酚、PPO和氯化亚铜(偶联催化剂)都有很高的溶解度。但像吡啶和硝基苯这样的溶剂是剧毒和有毒的。它们的使用存在健康、安全和环境问题，需要探索替代溶剂和技术。这项研究的目的是开发油-水界面合成，作为需要使用有毒溶剂的传统合成的一种良性替代。这项技术包括用无毒的油和水相结合来代替有毒的有机溶剂。以前限制溶剂选择的多种功能在这里是分离的，并由两相混合物单独满足。通过表面活性络合物和水相的pH控制，可以在油水界面上实现所需的反应。该项目将进一步发展界面技术，使其可以(1)优化并应用于商业PPO合成，(2)扩展到其他具有商业潜力的合成反应。这项研究将得到Mallinckrodt特种化学品公司的智力投入和可能的长期财政支持。

Organic syntheses are often carried out in organic solvents, some of which are toxic, hazardous, or environmentally troublesome. The choice of a solvent for a homogeneous synthesis reaction is often limited by the multiple functions required of the solvent. Two of the more important functions are: (1) solubilization of the reactants, reaction intermediates, and catalyst, and (2) rate or selectivity enhancement through the participation of the solvent as a base or as a catalyst ligand. In the aerobic coupling of 2,6- dimethylphenol, which is the basis of the commercial production of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO), pyridine and nitrobenzene are often used as the reaction media because of their high solubilities for dimethylphenol, PPO, and cuprous chloride (the coupling catalyst). But solvents such as pyridine and nitrobenzene are highly toxic and noxious. Their use presents health, safety and environmental concerns and alternate solvents and technology need to be explored. The objective of this research is to develop oil-water interfacial synthesis as a benign alternative to conventional syntheses that require the use of toxic solvents. This technique involves a combination of innocuous oil and aqueous phases in place of the toxic organic solvent. The multiple functions which previously limited the choice of solvent are here decoupled and are met separately by a biphasic mixture. The desired reaction is effected at the oil-water interface by means of a surface-active complex and by pH control of the aqueous phase. This project will further develop the interfacial technique so that it may be (1) optimized and adopted for commercial PPO synthesis and (2) extended to other synthesis reactions that have commercial potential. The research will receive intellectual input and possible long- term financial support from Mallinckrodt Specialty Chemicals Company.